The present invention relates to devices for recirculating exhaust gases, called exhaust gas recirculation (EGR), and more particularly to EGR gas devices that have an EGR gas cooler.
In order to improve the decontamination of exhaust gases of an internal combustion engine, use is made of exhaust gas recirculation into the intake, that is generally called an EGR circuit. Moreover, the use of specific coolers for these gases makes it possible to increase this decontamination still further.
However, a major problem is that exhaust gas recirculation brings about considerable fouling of components that are located within this EGR circuit. This is why cleaning/decarbonizing steps may be carried out by completely opening the EGR valve (the EGR valve regulates the flow of EGR gas which is distributed to the intake) when the engine is on a set operating zone. This method, described in application FR2833653, makes it possible to remove deposits thermally that accumulate in the EGR circuit.
This fouling problem is not however completely solved as regards the EGR cooler. The cooler is constantly operating, that is to say there is always a flow of water passing through the exchanger. What happens then is that the cooler is perfectly decarbonized at the inlet when a cleaning phase is carried out, but the EGR gases that are constantly cooled are not hot enough to decarbonize the EGR cooler completely, especially in the second half of the EGR water/gas exchanger.
Document JP20043400099 relates to an EGR system of an internal combustion engine having two separate sets of cylinders. This EGR system has the peculiarity of being able to reverse the flow of exhaust gas circulating in the duct and consequently in the coolers, by modifying the exhaust gas pressures between the first and second set of cylinders. A major disadvantage is that it is necessary to have two separate sets of cylinders available in which the exhaust gas pressures can be modified.